Everything will be fine. Overnight temps at 30F seemed warm here several weeks ago. It went down to the single digits for well over a week. The waterer froze solid until I decided to bring it inside every night. That worked much better, and I refilled with warm water in the morning. Chickens that are big enough/old enough do great. Even in our pathetic, hand-me-down coop, the 5 hens stayed together huddled on the roost for the long, dark, & cold nights and were out in the run before daybreak -- with poop frozen to their feet, sometimes! Poor things, but they were fat & hearty and never looked better. We always had the upper vents wide open, even in the freezing howling wind, cuz cold air is very dry and we wanted to keep it that way. Our coop has the thinnest of plywood for walls, and the walls don't even fit together properly. There are gaps everywhere. So, I stuffed bubble wrap into all the gaps to cut down on drafts as much as possible. Then, I wrapped part of the attached run with clear heavy plastic so to keep the freezing blasts of arctic air from gusting through their pop-door, which was open until I decided to shut it at night, too. The pop-door is right below their roost.
Lots of extra protein and healthy treats. They ate a lot. And I'm a believer in warm water ... they LOVED the warm water and they drank huge quantities of it. Egg production continued normally like nothing was going on. They free-ranged fine, even on the solid frozen ground, though they didn't scratch as much as usual because everything was hard and frozen. I made sure to fill their run with thawed chickweed, grass, and other greens and they got extra sunflower seeds and cracked corn. We had no heat, no light in the coop at night. But we DID add extra straw and shavings. As long as my hens are plump and healthy, when another cold snap hits us, I'll do it again.
Recently, overnight temps have been anywhere from 28F to 35F. On most early mornings, the ground is frosty and crunches underfoot, thawing by midday. Nothing special right now, it's normal winter weather.